1. Field of the Invention
The present invention relates to a developing roller that is incorporated into a developing device for use in an image-forming apparatus so as to transport and supply toner to an opposing area to a photosensitive member (a developing area), and more particularly, concerns a mono-component-developing-use developing roller.
2. Description of the Related Art
The mono-component-developing-use developing roller, which is a developing roller to be incorporated into a developing device of a mono-component developing system, charges toner in a gap between it and a toner-regulating blade, and transports and supplies the charged toner to a developing area while supporting the charged toner.
Conventionally, with respect to the mono-component-developing-use developing roller, those having an elastic layer and a surface-coating layer formed on a substrate have been well known, from the viewpoint of charge-applying capability to toner and durability. From the viewpoint of preventing separation of the surface-coating layer, it has been known that a primer layer is effectively formed between the elastic layer and the surface-coating layer. With respect to a primer material to form the primer layer, for example, a silane coupling agent is used (see Japanese Patent Application Laid-Open No. 11-190940 (0060th paragraph).
However, when the above-mentioned developing roller is used under a low temperature-low humidity environment, a problem of toner spillage occurs from the initial stage. The term “toner spillage” refers to a phenomenon in which toner supported on the surface of a developing roller and supplied to a developing area is spilled from the surface to contaminate the inside of an image-forming apparatus. Another problem is that when such a developing roller is used for a long time, fluctuations tend to occur in the amount of toner transport to the developing area between the developing roller and the photosensitive member due to an environmental change.